Mark the ring gear and turn the yoke and note how many rotations the yoke makes for one revolution the ring makes. Ding Ding. Based on how thick the ring gear is, it's at least a 4.10 and I bet the number of teeth for the pinion and ring is on the ring gear....if it's a 4.10, the teeth count would be 41 - 10
Looks to be cone load type which woulda been factory in "489" rearClutch or spring sure grip?